carl9170: remove fast channel change feature

Marco Fonseca reported a issue with his carl9170 device:
"I'm seeing a problem with the carl driver. If I change channels
repeatedly on the 2.4ghz band, monitoring (e.g. tcpdump) will
eventually halt.  I've seen this on various versions of the carl
driver/firmware (both from 1.9.4 to 1.9.7)"
<http://marc.info/?l=linux-wireless&m=136381302428113>

The culprit was identified as "fast channel change feature" which
according to Adrian Chadd is: "... notoriously unreliable and
really only fully debugged on some very later chips."
<http://marc.info/?l=linux-wireless&m=136416984531380>

Therefore, this patch removes the fast channel change feature.
The phy will now always have to go through a cold reset when
changing channels, but it should no longer become deaf.

Cc: Marco Fonseca <marco@tampabay.rr.com>
Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/carl9170/carl9170.h

@@ -70,12 +70,6 @@
 
 static const u8 ar9170_qmap[__AR9170_NUM_TXQ] = { 3, 2, 1, 0 };
 
-enum carl9170_rf_init_mode {
-	CARL9170_RFI_NONE,
-	CARL9170_RFI_WARM,
-	CARL9170_RFI_COLD,
-};
-
 #define CARL9170_MAX_RX_BUFFER_SIZE		8192
 
 enum carl9170_device_state {
@@ -599,7 +593,7 @@ int carl9170_led_set_state(struct ar9170 *ar, const u32 led_state);
 
 /* PHY / RF */
 int carl9170_set_channel(struct ar9170 *ar, struct ieee80211_channel *channel,
-	enum nl80211_channel_type bw, enum carl9170_rf_init_mode rfi);
+			 enum nl80211_channel_type bw);
 int carl9170_get_noisefloor(struct ar9170 *ar);
 
 /* FW */

drivers/net/wireless/ath/carl9170/debug.c

@@ -655,7 +655,7 @@ static ssize_t carl9170_debugfs_bug_write(struct ar9170 *ar, const char *buf,
 
 	case 'P':
 		err = carl9170_set_channel(ar, ar->hw->conf.channel,
-			ar->hw->conf.channel_type, CARL9170_RFI_COLD);
+					   ar->hw->conf.channel_type);
 		if (err < 0)
 			count = err;
 

drivers/net/wireless/ath/carl9170/main.c

@@ -939,7 +939,7 @@ static int carl9170_op_config(struct ieee80211_hw *hw, u32 changed)
 			goto out;
 
 		err = carl9170_set_channel(ar, hw->conf.channel,
-			hw->conf.channel_type, CARL9170_RFI_NONE);
+					   hw->conf.channel_type);
 		if (err)
 			goto out;
 

drivers/net/wireless/ath/carl9170/phy.c

@@ -1569,16 +1569,14 @@ static enum carl9170_bw nl80211_to_carl(enum nl80211_channel_type type)
 }
 
 int carl9170_set_channel(struct ar9170 *ar, struct ieee80211_channel *channel,
-			 enum nl80211_channel_type _bw,
-			 enum carl9170_rf_init_mode rfi)
+			 enum nl80211_channel_type _bw)
 {
 	const struct carl9170_phy_freq_params *freqpar;
 	struct carl9170_rf_init_result rf_res;
 	struct carl9170_rf_init rf;
-	u32 cmd, tmp, offs = 0, new_ht = 0;
+	u32 tmp, offs = 0, new_ht = 0;
 	int err;
 	enum carl9170_bw bw;
-	bool warm_reset;
 	struct ieee80211_channel *old_channel = NULL;
 
 	bw = nl80211_to_carl(_bw);
@@ -1592,31 +1590,12 @@ int carl9170_set_channel(struct ar9170 *ar, struct ieee80211_channel *channel,
 	/* may be NULL at first setup */
 	if (ar->channel) {
 		old_channel = ar->channel;
-		warm_reset = (old_channel->band != channel->band) ||
-			     (old_channel->center_freq ==
-			      channel->center_freq) ||
-			     (ar->ht_settings != new_ht);
-
 		ar->channel = NULL;
-	} else {
-		warm_reset = true;
 	}
 
-	/* HW workaround */
-	if (!ar->hw->wiphy->bands[IEEE80211_BAND_5GHZ] &&
-	    channel->center_freq <= 2417)
-		warm_reset = true;
-
-	if (rfi != CARL9170_RFI_NONE || warm_reset) {
-		u32 val;
-
-		if (rfi == CARL9170_RFI_COLD)
-			val = AR9170_PWR_RESET_BB_COLD_RESET;
-		else
-			val = AR9170_PWR_RESET_BB_WARM_RESET;
-
-		/* warm/cold reset BB/ADDA */
-		err = carl9170_write_reg(ar, AR9170_PWR_REG_RESET, val);
+	/* cold reset BB/ADDA */
+	err = carl9170_write_reg(ar, AR9170_PWR_REG_RESET,
+				 AR9170_PWR_RESET_BB_COLD_RESET);
 	if (err)
 		return err;
 
@@ -1633,11 +1612,6 @@ int carl9170_set_channel(struct ar9170 *ar, struct ieee80211_channel *channel,
 	if (err)
 		return err;
 
-		cmd = CARL9170_CMD_RF_INIT;
-	} else {
-		cmd = CARL9170_CMD_FREQUENCY;
-	}
-
 	err = carl9170_exec_cmd(ar, CARL9170_CMD_FREQ_START, 0, NULL, 0, NULL);
 	if (err)
 		return err;
@@ -1703,13 +1677,8 @@ int carl9170_set_channel(struct ar9170 *ar, struct ieee80211_channel *channel,
 	rf.delta_slope_coeff_man = cpu_to_le32(freqpar->coeff_man);
 	rf.delta_slope_coeff_exp_shgi = cpu_to_le32(freqpar->coeff_exp_shgi);
 	rf.delta_slope_coeff_man_shgi = cpu_to_le32(freqpar->coeff_man_shgi);
-
-	if (rfi != CARL9170_RFI_NONE)
 	rf.finiteLoopCount = cpu_to_le32(2000);
-	else
-		rf.finiteLoopCount = cpu_to_le32(1000);
-
-	err = carl9170_exec_cmd(ar, cmd, sizeof(rf), &rf,
+	err = carl9170_exec_cmd(ar, CARL9170_CMD_RF_INIT, sizeof(rf), &rf,
 				sizeof(rf_res), &rf_res);
 	if (err)
 		return err;
@@ -1724,9 +1693,8 @@ int carl9170_set_channel(struct ar9170 *ar, struct ieee80211_channel *channel,
 			  old_channel->center_freq : -1, channel->center_freq,
 			  err);
 
-		if ((rfi == CARL9170_RFI_COLD) || (ar->chan_fail > 3)) {
-			/*
-			 * We have tried very hard to change to _another_
+		if (ar->chan_fail > 3) {
+			/* We have tried very hard to change to _another_
 			 * channel and we've failed to do so!
 			 * Chances are that the PHY/RF is no longer
 			 * operable (due to corruptions/fatal events/bugs?)
@@ -1736,8 +1704,7 @@ int carl9170_set_channel(struct ar9170 *ar, struct ieee80211_channel *channel,
 			return 0;
 		}
 
-		err = carl9170_set_channel(ar, channel, _bw,
-					   CARL9170_RFI_COLD);
+		err = carl9170_set_channel(ar, channel, _bw);
 		if (err)
 			return err;
 	} else {